Electric contact plug



D. E. WADSW ORTH ELECTRIC CONTACT PLUG Filed march 1 1, 1958 3 Sheeig-Sheet 1 Jan. 21, 1941. D. E. WADSWORTH I ELECTRIC CONTACT PLUG Filed March 11, 1938 s sheets-sheet 2 2 o 1 1 w m w m 1 m 1 Z Z 7- A Q m 5 3 Q 5 /uq. 4/ i 5 a H a 5: H 2 I m T w B m mm v mm a a u w 5 J A 2 55a a I M a 6 2 m 6 w m... m

ATTORNEYS Filed March 11, 1938 3 Sheets-Sheet 3- 4 I lll| m "I msmni .19 $0 64 fl ml? M .INVENTOR I LDEJVANWRT/l ATTORNEYS f Patented Jan. 21, 1941 UNITED STATES PATENT, OFFICE ELECTRIC CoNTAoT PLUG Donald E. Wadsworth, Bloomfield, N. J. Application March 11, 1938, Serial No. 195,285

11 Claims.

"This invention relates to electrical Contact plugs .and more particularly to a dual purpose plu adapted to be used as a screw-in plug where an electrical connection is adapted to be made with a lamp or screw socket, for instance, and in other situations where an electrical contact is adapted to be made by Contact prongs.

It has heretofore been proposed to provide a dual purpose contact plug having a threaded conductive shell for reception in the screw socket and a contact centrally thereof for electrical connection with the center contact of the screw socket, while at the same time having a pair of Contact prongs adapted trical connection with the electrical contacts of electrical connectors, such as outlet prong plugin fittings. The pron-g contact elements have been relatively fixed but the portion carrying a threaded shell has prong contacts in one position and to conceal such contacts in another position. Prior attempts have, however, been rudimentary and no provision .has been made for retaining the parts in relative positions of adjustment. Moreover, all the contacts have been electrically alive in all positions of the pants.

One object of the present invention is a dual purpose contactplu-g wherein one or both contacts or terminals adapted for use in one situation are rendered inoperative when the plug is used in a different situation.

A further object of the present invention is to provide positive means for preventing rela tive displacement of the relatively movable component elements of a dual purpose Contact plug.

It is also an object of the invention to provide positive latching means adapted to be manually rendered inoperative before the characteristics of the contact plug may be changed.

The invention also seeks a contact plug which is practical from the standpoint of ease and cheapness of manufacture and durability in use.

These and other objects of the invention and the means for their attainment will be more apparent from the following detailed description, taken in connection with the accompanying drawings illustrating one embodiment by which the invention may be realized and in which:

Figure 1 is a viewin longitudinal section showing the dual purpose plug of this invention adapted for reception in a lamp socket;

Figure 2 is a view similar to Figure 1, but showing the parts in position for the utilization of prongs as the electrical connection; a

Figure 3 is a fragmentary longitudinal detail to enter and make elecbeen movable to expose the sectional view showing the position of the pants just after the end member has commenced to move to expose the contact pron-gs;

Figure 4 is a plan view showing the plug looking from above and taken in the plane indicated 5 by the line 4-4 of Figure 1 and looking in the direction of the arrows;

Figure 5 is a transverse sectional view taken in the plane indicated by the line 5-5 of Figure 1 and looking in the direction of the arrows;

Figure 6 iso, fragmentary view in side elevation, looking in the direction of the arrows 6-4 p in Figure 1.

Referring first to Figures 1 and 2; the dual purpose plug of this invention comprises a one 5 piece cup-shaped body comprising a hollow wall i0 and a bottom l3 defining 9. preferably, but not necessarily, cylindrical recess l2. The bottom 13 is formed centrally with an upstanding portion or boss l5 and, diametrically opposite thereto, with recesses which are disposed not only in the bottom, as indicated at H, but extending sliglitly into the side walls ID, as at 16, "to form pockets for the reception of leaf spring Contact latching means, hereinafter .to be described, when the plug is in the Figure 2 position.

In the bore i2 is adapted to reciprocate a slidable end portion IS, the bottom IQ of said portion abutting. in its inner position, the preferably fiat bottom surface l4 surrounding the boss l5 and on its outer periphery carrying a conductive shell 22 which is threaded for receptionin a screw socket, the material of the end portion 18 being conveniently molded to conform to the threads of the shell and retain it in position.

The end I! is formed with two substantially parallel longitudinally extending passages 25 which receive the respective upper ends of conductive contact elements or prongs 2-3 and 24 on which the end l8 slides and is guided. The prongs 23 and 24 are seated in longitudinally extending substantially parallel passages 21 formed in the boss IS, the upper surface of the boss being so shaped as to receive laterally bent portions 28 of the prongs and the lower surface of the bottom t3 being recessed, as at 30, to receive the bent ends 22 of the contact prongs 23, 24, as shown. Thus the ends 32 and the offset ortions 28 of the prongs lock or secure the prongs in the body member In. A screw-:34 is threaded into each end 22 by which electrical i conductors may be connected to the prongs, as will be understood.

The shell carrying end member I8 is formed 55 threaded end 31 of a central contact member 38, the threaded end 3'! passing through an aperture 40 in a striplike contact member indicated generally at 42. The upper surface of the movable end I8 is recessed, as at 44, whereby the strip 42 may be depressed into the recess, as at 45, to avoid contact with any conductive part of a screw socket and also to avoid electrical connection with the shell 22 and this depressed portion 45 of the strip is apertured, as at 46, to permit the passage of the prong 23. The aperture 46 is greater in all directions than the passage 25 and preferably fits down on a raised portion 41 surrounding the passage 25 to avoid any chance of direct elec-,

trical short circuit between the strip 45 and the prong 23, particularly when the shell "carrying member is in retracted position. The strip 42 then passes through a longitudinally extending passage 48 in the end l8 and enters a transverse passage 50 opening at each end outwardly of the plug, this passage being curvilinear or of cylindrical shape in the center portion thereof, as

shown at St, whereby to avoid contact with the prongs 23 and 24 and to providea receiving recess 5! for the boss i5 in the body member ill.

The passage 50, 5! is open at the bottom or may be considered as opening into two downwardly extending passage portions 52, 53. Into the passage portion 52 extends the lower end of the strip 42 which, in an intermediate portion, is bent outwardly, as at 5 5, to provide a thumb piece or the like accessible from the outside whereby the lower end of the strip 32 may be manipulated. From the finger piece 54, the strip extends downwardly, as at 55, and is then bent outwardly, as at 56, and reversely bent, as at 5?, the end portion 58 being upwardly bent and curved slightly at its end 59 to bear on one of the contact prongs, say, 23. The resiliency of the strip 42 is such that the reversely bent end 6E1) is normally urged against the inner surface ll of the wall it by reason of the contact of the end 59 with the prong and so that the end 56 may serve as a latching member to enter a recess 62 formed in the inner surface it near the rim of the cup-shaped portion l0. Obviously, this recess 62 may be of an extent only suflicient to receive the latching member 66 but for convenience in manufacture can be constituted as a continuous groove about the surface H of rectangular cross-section as an abutment.

In the opposite passage portion 53, a strip 66 is disposed, the upper end of which is secured in so that the end portion 69 and curved extremity some convenient fashion as by a rivet or the like 65 to the shell 22. This strip 54 is likewise of resilient and conductive material and is out wardly bent, as at 53, to provide a thumb piece exposed in the transverse passage 50 and a downwardly extending portion 66 and outwardly extending portion 61 which is reversely bent, at 68,

10 are substantially identical with the corresponding parts on the strip 42. Here again, the end 10 bears against the contact prong 24 to normally urge the latching portion 68 into the recess 62 and at the same time conduct electricity between the prong 24 and the conductive shell 22, as will be understood.

In Figure 1, the parts are shown in the position in which the contact plug would serve for electrical connection with a lamp socket or the like. To use the plug as a pronged plug, the two latching members 54 and 63 are pressed inwardly by the fingers, compressing the spring ends 58 and 69 to withdraw the latches 60, 66 from the recesses 62 and thereby permit the end I8'to be pressed downwardly into the cup-shaped body I0, as shown "in Figure 2. In this position, the latches 60 and 68 are received within the pockets I 6, l6 and serve again as latches in these recesses to retain the shell carrying member in the retracted position of Figure 2. At this time also the central contact 38 lies below the rim of the cup. Also at this time the contact portions 69 and 10 are in contact only with the nonconductive boss I5 so that no current may flow from the prongs 23, 24 to the shell or central contact 38.

The movable end member l8 may be moved to its extended position concealing the prongs 23, 24 by grasping the central contact 38 and'drawing the end l8 outwardly until the latches 60, 68 enter the recesses 62.

The lower end of the plug as viewed is conveniently closed by a cover member 94 having an edge interengaging with the edge of the pe- '97 by which the electrical conductors enter the recess formed by closure 94.

The operation of the dual purpose plug of Figures 1 through 6 should be apparent from. the foregoing description. Assuming the threaded shell member id to be in the retracted position of Figure 2 so that the prongs 23 and 24 are exposed for the purpose of insertion in a fitting, the electrical connections will thus be made directly from the prongs 23 and 24 to the electrical conductors secured, respectively, by the clamp screws At this time, the shell carrying membar it is retained in retracted position by means of the circumferentially s aced yielding or resilient latching devicesv 0r abutments 66, 6B which are resiliently retained in the recesses l6, it. Thus any separation or protrusion of the threaded shell carrying member from the plug is prevented as, for instance, when the plug is carried about in thehand. Also at this time the central contact member 38 is out of electrical connection with the prong 23 since theinclined surface H has cammed or deflected the contact member 59 and l9 away from the prongs 23 and 24 and now rei made with a screw socket or the like, the user may reach into the open mouth of the cup shaped body l0 and grasp the knob-like end 38 of the central contact member and withdraw the same outwardly. The resilient latch members 69 and 68 yield readily under the force exerted in withdrawing the threaded shell member and follow the inclined contour 2| of the lower end of the surface ll. As the shell carrying member is drawn outwardly, the contact fingers 59 and I0 move into contact with the prongs 23 and 24, respectively, by reason of the camming action of the surface II which is of relatively reduced diameter as compared with the inclined portion 2| of the recess so that the contact members 59 and v v 2,229,150 fact that the springs formed by the parts 58 and 69 are under compression, as shown in Figure 3. Thus the latching members shell carrying member in outward position. In the position of the parts shown in Figure 1, the electrical circuits are readily traced. Thus electrical current may flow from the threaded shell carrying member 22 through the conductive finger 64 and wiping contacts 69, 10 to the prong 24 and thence to the electrical conductor secured thereto by the clamping screw 34. Similarly, current flowing from the central contact 38 travels through the conductive strip 45, 42 and wiping contact 59, 58 to the prong 23 and thence to the electrical conductor connected to the clamping screw 34 at the end of this contact prong 28.

It will thus be seen that a dual purpose plug has been provided in which the reciprocating end member or shell carrying member is releasably retained in either protracted or retracted position and that in retracted position the contact parts, which function when the plug serves as a screw-in plug, are out of electrical connection,

that, in no circumwith the contact prongs so stances, can current be carried thereby, position of the parts.

Various modifications will occur to those skilled in the art in the composition, configuration and disposition of the component elements going to make up the invention as a whole as well as in the selection of features for use in other combinations and no limitation is' intended by the in this 7 phraseology of the foregoing description or illustrations, in the accompanying drawings, except as indicated in the appended claims.

What is claimed is: 1. In an electrical contact plug, in combination, a hollow cup-shaped body member formed on the inner surface of its bottom with spaced pockets,

the inner surface of the body proximate the rim being recessed, two spaced substantially parallel conductive contact prongs secured in the body, an end member of a cross-sectional area to enter the body member and formed with spaced longitudinal passages to receive the prongs, respectively, a threaded conductive shell carried with the end member for reception in a screw socket, said end member being formed with circumferentially spaced recesses, longitudinal passages from the lower. surface of the end-member to the recesses, respectively, a resilient conductive contact member comprising a strip of material in the recess and passage, one end of which is secured to the shell and formed with an outwardly bent portion disposed in one recessand a transversely bent portion therebeneath to enter the recess in the body member and a contact portion in the passage adapted to engage a contact prong, a central contact removably secured to the exposed end of the end member, a second resilient conductive contact member 'one end of which is electrically connected to and positioned by the central contact and formed with a passage in register with the other contact prong and a portion passing through another longitudinal passage formed in the end member and formed with an outwardly bent portion disposed in a recess and a transserve to retain the ,posed in said passage and a therebeneath movable to enter .said recess in the socket, a central contact carried by the end mem- I ber, said end member being formed with recesses, 10

resilient conductive contact members respectively electrically connected with the contacts and in sliding engagement with the prongs, said conductive members each having a thumb piece dislatching portion member.

in combinabody member to position the end 3. In an electrical contact plug,

tion, a hollow cup-shaped body member formed with a substantially central boss integral there- 20 with and of materially greater thickness than the bottom wall thereof and extending upwardly from the inner surface of the bottom wall within the peripheral wall of the cup-shaped body, two

spaced substantially parallel conductive contact 25 prongs disposed within said cup-shaped portion and passing through said boss, spaced portions of each prong being bent laterally respectively above and below the boss and in contact therewith to secure said prong to the cup-shaped body 30 member and a threaded shell carrying end member movable into and out of the body member and formed with a recess to receive the boss in its retracted position.

4. In a dual purpose electrical contact plug, in 35 combination, a hollow cup-shaped body member, the inner surface of the body member being formed with a shoulder, two spaced substantially parallel conductive contact prongs mounted within the body'member and projecting therewith- 40 out, an end member of a cross-sectional area to enter the body member and formed with spaced longitudinal passages slidably receiving the prongs, respectively, an electrical contact carried with the end member for engagement with a socket contact, a conductive resilient member disposed within the body member and electrically connected with the contact on the end member and having a portion to contact a prong whereby to complete a circuit between the prong and 50 the said contact,,said conductive resilient member being formed with a portion adapted to engage the shoulder on the body member when the end member is in one extreme position to limit movement of the'end membe 5. In a dual purpose electrical contact plug, in combination, a cup-shaped body member, the inner surface of the body member being formed with a shoulder proximate the rim and a shoulder inwardly thereof, two spaced substantially parallel conductive contact prongs secured in said body member and projecting .therewithout, an and member of a cross-sectional area to enter the body member, an electrical contact carried with the end member for engagement with a socket contact, a resilient conductive member comprising a strip of conductive material one end of which is'eiectrically connected to the contact and a portion of which contacts a prong to electrically connect the contact and the prong, said resilient member being formed with a portion adapted to engage a shoulder in either position of the end member.

6. A dual purpose electrical contact plug comprising a cup-shaped body member formed with axially spaced recesses, spaced contact prongs carried within the body member and fixed thereto and of a length to extend therewithout, a threaded shell-carrying end member reciprocable into and out of the body member, a threaded conductive shell and a central contact carried by the end member for reception in a screw socket and means to retain the end member in its retracted' and protracted positions, respectively, comprising resilient conductive members respectively electrically connected with the shell and central contact and in sliding conductive relation with the respective contact prongs and respectively having a portion to be received in one of the recesses in retracted and protracted position.

7. A dual purpose electrical contact plug comprising a cup-shaped body member formed with a recess, spaced contact prongs carried within the body memberd and fixed thereto and of a length to extend therewithout, a thread shell-carrying end member reciprocable into and out of the g body member, a threaded shell and a central contact carried by said end member for reception in a screw socket and yielding means having a portion to be received in the recess to retain the shell carrying member in one position comprising resilient conductive members electrically connected respectively with the central contact and the threaded shell and in sliding conductive relation with the respective prongs.

8. A dual purpose contact plug comprising a cup-shaped body member, spaced contact prongs carried therewithin and extending therewithout, an end member reciprocable into and out of the body member, a threaded shell on the end memher, a central contact member carried by the end member, means to electrically connect the threaded shell with one contact prong, means to electrically connect the central contact member with the other contact prong, and means to interrupt said connections when the shell carrying member is retracted.

9. A dual purpose contact plug comprising a cup shaped body member, spaced contact prongs carried therewithin and extending therewithout, an end member reciprocable into and out of the body member, a threaded shell on the end member, a central contact member carried by the end member, yielding contact means electrically connecting the threaded shell with one contact prong, yielding contact means electrically connecting the central contact member with the other contact prong, and cam means to deflect the yielding contact means from the prongs to interrupt said connections when the shell carrying member is retracted.

10. A dual purpose contact plug comprising a cup-shaped body member, spaced contact prongs carried therewithin and extending therewithout, an end member reciprocable into and out of the body member, a threaded shell carried by the end member, a central contact member, conductive means to electrically connect the threaded shell with one contact prong, conductive means to electrically connect the central contact memher with the other prong, at least one of said conductive means and the body member respectively comprising coating means to retain the shell carrying member in one position and means to interrupt said connections, when the shell carrying member is retracted.

11. A dual purpose contact plugl comprising a cup-shaped body member, spaced contact prongs carried therewithin and extending therewithout, an end member reciprocable into and out of the body member, a threaded shell carried by the end member, a central contact member, conductive means to electrically connect the threaded shell with one contact prong, conductive means to electrically connect the central contact member with the other prong, at least one of said conductive means comprising yielding means to retain the shell carrying member in either its innermost or outermost position, said body member comprising means to coact with said retaining means and means to interrupt said connections when the shell carrying member is retracted.

DONALD waoswoa'in. 

